The purpose of this project is to identify and evaluate carcinogenic hazards of chemical agents in the environment and to conduct research to improve methodology of carcinogenesis bioassay and increase its capabilities as a predictive science. For the most part the carcinogenesis tests consist of using standardized long-term animal bioassays in which both sexes of two species are exposed to the agent for a major portion of its lifespan, i.e., 18-24 months. Usually two dose levels are used with extensive pathology examination performed on all animals. The majority of the actual testing is conducted through contracts with the Program staff responsible for developing the required resources, protocols, monitoring of progress and establishing methods of reporting results.